The invention relates to a drive unit.
A drive unit is known from DE 10 2010 064 295 A1 belonging to the applicant. The known drive unit is part of a comfort drive in a motor vehicle, such as, for example, in a power window drive, a sliding roof drive, a seat adjustment drive. In particular, the known drive unit has a first and a second bearing element on both sides of a drive motor in order to support a drive shaft. The drive shaft interacts with a worm toothing having a mating toothing of a gear wheel designed as a spur gear. A third bearing element is provided on that side of the gear wheel which faces away from the drive motor, the bearing element serving to absorb or to support forces which act transversely with respect to the longitudinal axis of the drive shaft and lead to a deflection of the drive shaft. For this purpose, the known drive unit or the third bearing element thereof has a portion which engages around the drive shaft at the circumference thereof preferably with radial play and is connected via a flexible intermediate portion to a bearing region arranged in a receptacle of a gear housing. As seen overall, the single-part third bearing element is of sleeve-shaped design with a passage opening for receiving the end region of the drive shaft. It is disadvantageous in the case of the drive unit known from the document mentioned that the third bearing element, for the mounting thereof, requires a relatively large amount of space in the gear housing since the third bearing element, as seen over its entire circumference, is arranged in a corresponding receptacle of the gear housing. Furthermore, the required space for receiving the third bearing element restricts the construction space or the possibility of an axial support for the end region of the drive shaft or makes such an axial support no longer possible. It should furthermore be considered to be particularly disadvantageous that, in the event of radial play between the circumference of the drive shaft and the third bearing element, a periodic contact or striking of the circumferential surface of the drive shaft against the third bearing element occurs, typically because of component tolerances, which may be perceived as an annoying noise.